Adaptive cruise control maintains a driver-selected vehicle speed or maintains a driver-selected headway to a preceding licensable vehicle moving slower than the driver-selected vehicle speed. Adaptive cruise control automatically switches between speed control and headway control based on the presence of a preceding licensable vehicle moving slower than the driver-selected vehicle speed. Speed control and headway control are accomplished by powertrain control (e.g. adjusting the throttle) or applying limited automatic braking.
Adaptive cruise control can be engaged by the driver using the cruise control switches when vehicle speed is above a minimum engagement speed, for example twenty-five miles per hour (MPH). When speed drops below a minimum value, for example twenty MPH, adaptive cruise control begins to disengage. While adaptive cruise control is disengaging, automatic braking can continue to be applied but adaptive cruise control does not accelerate the vehicle.
Full speed range adaptive cruise control (FSRA) extends the operation of adaptive cruise control down to a stop. Once FSRA brings the vehicle to a complete stop, the vehicle will remain stopped until the driver indicates it is alright to go. The driver accomplishes this by pressing the accelerator pedal or by pressing a cruise resume switch. Like adaptive cruise control, FSRA is a convenience feature that is designed to follow vehicles. When FSRA has brought the vehicle to a stop, the driver is responsible for indicating the path ahead is clear of objects, for example pedestrians, that may not be detected by the FSRA system.
Adaptive cruise control has been designed to allow the driver to be considered part of the hazard mitigation strategy. Part of this design limits the vehicle acceleration and deceleration capabilities so the driver can take over when needed. The low speed operation of FSRA also assumes the driver would be able to override the system. This includes low speed operation following the vehicle coming to a complete stop. However, because there is potential for the driver to get out of the vehicle or be out of position, for example, reaching in the back seat, while the FSRA system is holding the vehicle at a stop, it may be desirable to provide improved techniques to help ensure that only pre-defined deliberate driver actions allow the FSRA system to release the brake hold and/or to help ensure that failure modes are not inadvertently interpreted as valid driver actions leading to release of FSRA from a stop.
Accordingly, it is desirable to provide an improved method for implementing adaptive cruise control for vehicles, for example that helps to ensure that only pre-defined deliberate driver actions allow the FSRA system to release the brake hold and/or that helps to ensure that failure modes are not inadvertently interpreted as valid driver actions leading to release of FSRA from a stop. It is also desirable to provide an improved program product for such improved implementations of adaptive cruise control. It is further desirable to provide an improved system for such improved implementations of adaptive cruise control. Furthermore, other desirable features and functions of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.